System of motor control.



No. 649399. Patented May l5, I900.

O W. LARSON. SYSTEM OF MOTOR CONTROL.

(Application med Mar. 30, 1900.)

(-No Model.)

I I In 1G Jnvenbor. Carl W Carson.

UNITED STATES PATENT OFFIcE.

CARL W. LARSON, OF SCHENECTADY, NEW YORK, ASSIGNOR TO THE GENERALELECTRIC COMPANY, OF NEIV YORK.

SYSTEM OF MOTOR CONTROL.

PECIFICATION forming art Of Letters Patent NO. 649,699, dated May 15,1900.

Application filed March 30, 1900- erial No. 103728. (No model.)

To all whom it may concern.-

Beit known that I, CARL W. LARSON, a citizen of the United States,residing at Schenectady, county of Schenectady, State of New York, haveinvented certain new and useful Improvements in Systems of MotorControl, (Case No. 1243,) of which the following is a specification.

My invention relates to a system of motor control, and has for itsobject to provide a simple and effective means for so controlling thecircuit connections between the motor and its source of supply that thesaid circuit will be opened whenever a device operated by the motorreaches a certain definite position in its movement.

I have illustrated my invention in connection with a drawbridge,although it is equally applicable in connection with any movable devicethat requires a positive support in one of its operative positions. Indrawbridges as at present contructed 'it is necessary that some meansshould be provided for supporting the free end of the draw when it is inits closed position, so as to prevent vibration of the same as heavyloads are carried over it, andin heavy structures this supportingmeansgenerally comprises a heavy mechanism operated by some type of motivedevice. In operating the draw it is therefore necessary, before settinginto operation the means for turning the drawbridge on its pivot orwithdrawing it from proximity to the end of the bridge, to first set inoperation a motive device for withdrawing the support under the free endof the draw and when such support has been sufficiently withdrawn tostop said motive device. After this support has been withdrawn power maybe supplied to the main motive device for opening the draw. Similarlyafter the draw has been closed it is necessary to set in operation themotive device for replacing the support, and the operator must becareful to shut off the power from this motive device when the supporthas been replaced. By my invention I provide means for bringing to restthe motor actu ating the support whenever the said support reacheseither extreme of its movement, no attention on the part of the operatorbeing required except to start the motor into operation.

Referring to the drawings accompanying this specification, Figure 1illustrates, diagrammatically, the controlling switches and circuitconnections arranged according to my invention; and Fig. 2 illustratesan application of my invention to a drawbridge.

Referring to Fig. 2, G represents aportion of a bridge adjacent to theend of the draw, and H represents the drawbridge itself,whiel1 mayevidently be of any desired type, either sliding or swinging. draw andmounted on an abutment at the end of the bridge are supports I I,carrying bearin gs in which is mounted a shaft 8, this shaft carrying aplurality of eccentrics K, which engage with proper bearing-surfaces(not shown) on the timbers of the drawbridge and constitute a supporttherefor.- The shaft .5

is operated by means of a motor M, geared thereto by means of aworm-gear. The shaft carries also, mounted on an insulating-support, aconducting-strip E, arranged to bridge the contacts 9 h or the contactsZ, which latter are mounted upon an insulating-support L, according asthe shaft 3 is in one or the other of its extreme positions. In theposition of parts illustrated in Fig. 2 of the drawings the eccentrics Kare in position to support the draw and the conducting-strip E is inposition to bridge the contacts g it. When the shaft 8 is in such aposition that the eccentrics K no longer rest against the lower side ofthe draw, the contact-strip E will bridge the contacts 7c Z.

I have shown in Fig. 1 the switching device and circuit connections thatare required to operate the supports K in the manner already described.Referring now to Fig. 1, A indi cates the armature of the motor M, and FF its field-windings. C indicates the main con-' troller, by means ofwhich the motor M is controlled in its operation. RS indicates thereversing-switch for changing the relative connections of the armatureand field windings of the motor. D indicates the circuitbreaker, whichmay be of any suitable construction, but which is provided with ahighresistance actuating-coil adapted to be con- Beneath the end of thenected in shunt to the mains. E indicates the bridging-contact, alreadyreferred to, which operates to connect the actuating-coil of thecircuit-breaker D across a source of current-supply in the extremepositions of the shaft 8 in a manner to be hereinafter more fullydescribed. The controller 0 and reversing-switch RS comprise fixedcontacts (indicated by the small circles) and movable contacts,(indicated by the rectangles,) all the contacts being shown developed ona plane surface, as is customary in illustrating such structures,although in actual construction the movable contacts are commonlymounted upon the surface of the cylinder and are suc cessively broughtinto engagement with the fixed contacts as the cylinder is actuated. Thecircuit-breaker D may be of any desired construction, but I preferablyuse the form described in Patent No. 567,137 to E. M. Hewlett, the onlydifference being that I provide the circuit -breaker with anactuating-coil having high resistance and adapted to be connected inshunt to a circuit instead of a low-resistance series coil, as is shownin said patent.

Assuming the parts to be in the position shown in Fig. 2, with thecontact-strip E bridging the contacts ,1 and h, if it is desired tooperate the motor M to move the supports K the reversing-switch RS willbe moved until the contacts I) Z) are in engagement with thecorresponding fixed contacts 10 to 13, inclusive, and the controller Cwill then be moved until in its first position the movable contacts 1,2, 8, and 9 are brought into engagement with the corresponding fixedcontacts. In this position of the controller the circuit connections maybe traced as follows: Starting from'the plus main the circuit leadsthrough the movable switch member d of the circuit-breaker D to thefixed members 6 c, thence through the blow-out coil B of the controller0 to fixed contact 1, by way of cross-connected contacts 1 2 to fixedcontact 2, by way of cross connection to fixed contact 9, throughcross-connected contacts 9 and S to fixed contact 8, thence throughresistance R to fixed contact 10 of the reversing-switch, by way ofcontact Z) to fixed contact 11, through the armature A of the motor M tofixed contact 12 on the reversing-switch, and by way of contact I) tofixed contact 13, and through the sections F F of the fieldwindings ofthe motor to the minus main. In this position of the switches a circuitmay also be traced from the positive main through the movable switchmember (1 of the circuitbreaker D and through the fixed members 6 e tothe actuating-coil f of the said circuitbreaker, through contacts g andh, by way of the bridging-conductorE to the fixed contact 16 on thereversing-switch, by way of movable contact 72 to fixed contact 17, atwhich point this circuit joins the circuit already traced, the actuatingcoil of the circuitbreaker being thus connected in shunt to the armatureof the motor M. As will be seen by referring to the construction shownin the patent to E. M. Hewlett above referred to, the actuating-coil foperates to withdraw a detent normally in engagement with a projectionon the spring-actuated switch-lever (1, so that until the actuating-coilis sufficiently energized the switch-lever is maintained in the positionshown in the drawings. \Vhen the actuating-coil fis shunted around thearmature of the motor M, as is the case when the motor is started intooperation, the current flowing through the actuatingcoil fisinsuffieient to withdraw the detent from, the switch lever d, and thecircuitbreaker therefore remains closed in the position shown in thedrawings. As the controller O is moved to its final position thesections of resistance R are gradually cut outin a manner wellunderstood and the motor M is caused to operate at full speed to rotatethe shaft .9 and to remove the supports K. As soon as the motor hasstarted into operation the bridging-con tact E will be withdrawn fromthe contacts 9 hand the motor will continue to run until the saidcontact bridges the contacts 7t Z. When this occurs, a circuit will beclosed through the actuating-coil of the circuit-breaker, as follows:starting from the plus main, through the switch members of thecircuit-breaker to the actuating-coilf,through the contacts and 7-, byway of the bridging device E to fixed contact 15 on the reversingswiteh,and by way of movable contact b to contact 14: and back to the minusmain. The actuating-coil of the circuit-breaker will therefore besupplied with the full potential of the system and will operate toWithdraw the detent from engagement with the springactuated lever d, andthe said lever will be thrown into the position shown-in dotted lines,thereby opening the main circuit to the motor M and causing the same tocome to rest. If new the controller 0 is thrown to its off position andthe reversing-switch RS thrown so as to bring its contacts 0 and 0' intoengagement with the contacts 10 to 13, inclusive, the circuit-breakermay be closed and the system will be in condition when again thecontroller 0 is thrown into operation to drive the motor M in such adirection as to replace the supports K in their operative position. Withthe reversing-switch in this position, with its contacts 0 and cengagingthe fixed contacts 10 to 13, the connections for themotor-circuit will be the same as those already described, except thatthe relative direction of current-flow in the armature and fieldwindings of the motor will be reversed, and, as before, a branch circuitmay be traced through the actuating-coil of the circuitbreaker in shuntto the armature of the motor. The energizing-coil of the circuit-breakerwill not, however, be supplied with full potential until the contact Ehas been again brought into engagement with the contacts g and it, atwhich time a circuit will be closed.

from the plus main through the switch members of the circuit-breaker,and through the actuating-coil of the circuit-breaker through thecontacts g h, by way of bridging-contact E to fixed contact 16 on thereversing-switch, and by way of cross-connected movable contact c tofixed contact 14: and the minus main, when the circuit-breaker D will beopened, as before. It will be noted that although the fixed contacts 14to 17, inclusive, and movable contacts b b 0 and c are shown associatedwith the contacts on the reversingswitch they form no part of the sameand might, if desired, be mounted on a separate structure. Thesecontacts control only the circuit connections of the contacts h and Z;but since it is necessary that they should be actuated at the same timethe contacts of the reversing-switch are actuated they are preferablycombined in the same structure with the reversing-switch.

I have shown the two sets of contacts cooperating with the bridgingdevice E as comprising each two contacts; but it is evident that thecontacts 9 and 79 might be omitted, if desired, in which case theterminal of the actuating-coil fwould be connected directly to thebridging device E. Other modifications in details may evidently be madewithout departing from the spirit of my invention, and all suchmodifications I intend to include in the scope of the following claims.

\Vhat I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. In combination, a movable body, a device to be moved constitutingasupport therefor, a motiy e device for moving said support intoengagement with and for withdrawing it from said body, and meanscontrolled by the movement of said support in either direction forstopping said motive device.

2. In combination, a movable body, a device to be moved constituting asupport therefor, a motor for operating said device, a circuit-breakerin the circuit of said motor, an actuating-coil therefor, and meanscontrolled by the movement of said support, for energizing saidactuating-coil.

3. In combination, a movable body, a device to be moved constitutingasupport there- ;for, a motor for operating said device, acircuit-breaker in the circuit of said motor, an actuating-coiltherefor, a plurality of contacts, means in operative relation to saiddevice for closing a circuit from one side of a source of supply throughsaid actuating-coil to one or the other of said contacts, and a switchfor connecting one or the other of said contacts to the other side ofsaid source.

4. In combination, a device to be moved, a motor for operating saiddevice, a circuitbreaker, an actuating-coil therefor, two sets ofcontacts, means in operative relation to said device for bridging eitherof said sets of contacts, and a switch for operatively connecting saidactuating-coil to a source of ourrent-supply through one or the other ofsaid sets of contacts.

5. In combination, a device to be moved, a motor for operating saiddevice, a source of current-supply, a circuit-breaker, anactuating-winding therefor, two sets of contacts, means carried by saiddevice for bridging one or the other of said sets of contacts, areversing-switch in said motor-circuit, and contacts carried by saidreversing-switch for connecting the actuating winding of thecircuitbreaker across the source through one or the other of said setsof contacts.

6. In combination, a device to be moved, a motor for operating saiddevice, a circuitbreaker in the circuit of said motor, an actuating-coiltherefor, two sets of fixed contacts, a connection from one terminal ofsaid actuating-coil to one side of a source of current-supply, aconnection from the other terminal of said coil to a contact in each ofsaid sets of fixed contacts, means for connecting the remaining contactof either set to the other side of said source, and means actuated bythe device to be moved for bridging the contacts of either of said sets.

7. In combination, a device to be moved, a motor for operating saiddevice, a circuitbreaker in the circuit of said motor, an actuating-coiltherefor, two sets of fixed contacts, a connection from one terminal ofsaid actuating-coil to one side of a source of current-supply, aconnection from the other terminal of said coil to a contact in each ofsaid sets of fixed contacts, a reversing-switch in said motor-circuit,contacts carried by said reversing-switch for connecting the remaining.contact of either of said sets of fixed contacts to the other side ofsaid source, and means actuated by the device to be moved, forbridgingsaid contacts.

8. In combination, a device to be moved, a motor for operating saiddevice, a circuitbreaker in the circuit of said motor, an actuating-coiltherefor, two sets of fixed contacts, a connection from one terminal ofsaid actuating-coil to one side of a source of ourrent-supply, aconnection from the other terminal of said coil to a contact in each ofsaid sets of fixed contacts, a reversing-switch in said motor-circuit,means operated simultaneously therewith for connect-ing the remainingcontact of either of said sets of fixed contacts to the'other side ofsaid source, and means actuated by the device to be moved, for bridgingsaid contacts.

In witness whereof I have hereunto set my hand this 28th day of March,1900.

CARL lV. LARSON.

Witnesses:

BENJAMIN B. HULL, ALnx F. MAonoNALn.

